The damage did not compromise safety or impair the function of the machines, which have a total of 31,000 tubes, DeSantis said.

According to documents furnished by TMI and forwarded by Epstein, one of the old generators was 10.9 percent plugged while the other was 5.9 percent plugged.

TMI is 35 years old, DeSantis noted, and most of the plant's other major components have already been updated.

The old generators are at the end of their useful life, he added.

Classified as low-level radioactive waste, they will be stored at TMI in a "specially designed building" until the plant is decommissioned, DeSantis said.

The $300 million generator replacement project is part of a larger overhaul that will entail hiring 3,000 workers and temporarily closing TMI this fall while the reactor is refueled and the new equipment installed, DeSantis added.

The work is being done in anticipation of relicensing by the federal Nuclear Regulatory Commission, which DeSantis said could come as early as the end of this year and extend TMI's lifespan until 2034.

All of which exacerbates the problem of what to do with growing stockpiles of nuclear waste, in Epstein's view.

"The old plants are the new reactors," he said, dismissing reports of a nuclear energy resurgence. "The island is going to host radioactive waste well into the next century."